There is conventionally known an electro-photographic type image forming apparatus such as a laser printer and an LED printer. A developing cartridge is used for the image forming apparatus. The developing cartridge includes a developing roller for supplying toner.
The developing cartridge in a prior art is configured to be attached to a drum cartridge. The drum cartridge includes a photosensitive drum. In a state where the developing cartridge is attached to the drum cartridge, the photosensitive drum and the developing roller of the developing cartridge are in contact with each other. Then, the drum cartridge to which the developing cartridge is attached to the image forming apparatus in a state where the developing cartridge is attached to the drum cartridge.